This invention relates to a liquid crystal display device and, more particularly, to an active matrix liquid crystal display device.
As will later be described, a conventional active matrix liquid crystal display device of the type described, comprises a liquid crystal panel. The liquid crystal panel comprises an insulating film and a plurality of thin-film transistors, each of which has a drain electrode and a source electrode.
Each of drain lines is of a first conductive material. The drain lines are formed on the insulating film and connected to the drain electrodes of the thin-film transistors, respectively.
Each of the display electrodes is of a second conductive material which is different from the first conductive material. The display electrodes are formed on the insulating film and connected to the source electrodes of the thin-film transistors, respectively.
Inasmuch as the display electrodes are different in material from the drain lines, the display electrodes and the drain lines are formed at different patterning steps. As a result, positioning errors inevitably occur between the drain lines and the display electrodes. This results in non-uniformity of capacitances between the drain line and the display electrode for one of the thin-film transistors and between the display electrode for the thin-film transistor in question and the drain line for an adjacent one of the thin-film transistors. The adjacent one of the thin-film transistors is nearer the display electrode for the thin-film transistor in question rather than the drain line for the thin-film transistor in question.
Inasmuch as the non-uniformity of the capacitances results in degradation of display quality of the display device, it is required to compensate for the non-uniformity of the capacitances.
In Japanese Utility Model Publication No. B586/1993, another display device is disclosed which comprises auxiliary lines, each of which is of the second conductive material. The auxiliary lines are formed on the drain lines simultaneously with the display electrodes. However, inasmuch as each auxiliary line has the same shape or width as each drain line has, it is difficult to compensate for the non-uniformity of capacitances between the drain line and the display electrode for the thin-film transistor in question and between the display electrode for the thin-film transistor in question and the drain line for the adjacent one of the thin-film transistors that is adjacent to the display electrode for the thin-film transistor in question.